Conservation, hackspaces and Raspberry Pis. And sharks. How could this not be the blog of the day? Gary Fletcher of ZSL sent us this report.

Marine Conservation Camera

ZSL have developed low cost cameras to monitor marine biodiversity in large marine protected areas (MPAs) using the $35 Raspberry Pi single board computers and standard webcams and running opensource Motion tracking software. ZSL reached out to UK hackspaces to help design the cameras and achieved unprecedented economy and features.

Why Raspberry Pi?

Traditionally it has been incredibly difficult to capture events underwater – all of the usual apparatus such as PIR/heat, infrared and ultrasonic sensors simply do not work underwater. The Raspberry Pi literally opened up a new door with its low power consumption and processing power. It allowed us to deploy a solution which really fits the bill and without it would have been very troublesome to achieve!

Hardware

Each camera was deployed on an anchored buoy. Mounted directly onto the buoys were two solar panels for charging two deep cycle 90Ah lead-acid gel batteries, the aerial, and a waterproof box containing the communications system. This was then connected to a 50m SWA cat-5 cable running down to the pressure vessel containing the camera itself.

Pressure Vessel

The cameras are designed to operate at depths between 20 and 50 meters. Rlab’s (Reading Hackspace) Ryan White suggested basing the design around a clear polycarbonate tube, with machined HDPE end caps secured by threaded rods and double o-rings. One end-cap had a threaded hole which SWA cat- 5 cable was run though, anchored to the inside and then potted. This cable runs the power and communications.

BuildBrighton’s Mike Poutney and Paul Strotten machined the endcaps on their lathe and offered some great technical advice which was very well received.

The outer pressure vessels easily survived a 100m pressure test in a hydrostatic chamber. It should go significantly deeper had the internal structure not failed at that point.

Internal Structure

Rlab’s (Reading Hackspace) Barnaby Shearer designed the internal support structure. This was laser cut from 3mm acrylic. The designs were done in 3D in OpenSCAD to check all the components fitted together, then projected into 2d for laser cutting. The acrylic was glued with tensol.

Cable waterproofing

The junction box was 3d printed and then sealed using potting compound and left to dry for some time also forming a mechanical join between the inside and the cable gland.

Communications

Attached to the buoy in a waterproof case was a Raspberry Pi to coordinate the communications. This had an Ethernet link to the Raspberry Pi in the pressure vessel. It also had a WiFi dongle running in access point mode to allow easy monitoring and reconfiguration form the research vessel. The Pi also has a serial connection to an Iridium satellite modem so it can stream pictures of the images captured.

The satellite image transfer software was specially developed by Cambridge Consultants and the equipment and satellite bandwidth for this trip was kindly sponsored by Iridium.

Electronics

Attached to the bottom Pi was an Eve board to provide the Pi a RTC and a temperature sensor. Also attached was Ciseco’s Humble Pi hosting an AVR and a mosfet to to turn the Pi off at night (and critically back on each morning). This Pi wake was developed by Miles and Matt from Ciseco, who make an amazing range of Raspberry Pi and microelectronics and are well worth a look – http://www.ciseco.co.uk/

These boards were slightly modified to handle a HackHD camera via the AVR so we could capture high definition footage as well as stills.

The boards were assembled at Nottingham Hackspace.

Camera

The camera used is the Microsoft LifeCam Cinema HD, a cost effective camera conforming to the UVC specification. The only gotcha proved to be that it seems to only respond to a few ‘magic’ exposure settings (5,10,20,39,78,156,312,625,1250,2500,5000,10000,20000), and you have to wait 100ms and reset the brightness after any exposure change.

Software

Rlab (Reading Hackspace), Gary Fletcher and Doug Snead provided a simple command line program to control the camera, and a slimmed down version of MJPEG-Streamer optimized for this camera and with some additional time stamping.

This stream then fed into Motion which starts saving the frames as JPEGs after it detects an event. The JPEGs are then rsynce’d up to the top Pi (backups are always a good thing). ImageMagick then thumbnails and montages the images for efficient sending over the (slow) satellite link.

Stereo Vision

The project did spur off onto some stereo vision development work with Doug Snead and Gary Fletcher but could not be completed in time for deployment. It was hoped that it would be possible to develop this solution as so it could automatically size the passing fish to add to our conservation data.

Image showing the accurate sizing of a fish tied to the ceiling flapping in front of an oscillating fan.

What did it Look Like

The deepest ever Pi?

At 50 meters deep – could this be the deepest Pi to date?

Where was it Deployed?

The system was tested at ZSL in London Zoo behind the scenes and then went onto to open Ocean tests in the largest marine protected area in the world, the Chagos Archipelago.

Gary Fletcher and Barnaby Shearer test the camera at ZSL London Zoo, behind the scenes

Results

Well as you can see the results speak for itself, but there is still quite a lot of development work to do but once these sentient units are complete, it will offer a low-cost monitoring system that, when deployed as a network, will greatly expand ocean areas that can be observed.

This is awesome! Not just because it’s sending Pi’s into battle on the front line of environmental monitoring, but as a demonstration of what can be achieved in a Hackspace environment. Having encountered them recently, via Oxford Raspberry Jam, and Thames Valley RepRap User Group, I’m joining Reading Hackspace right now, and it’s because of projects like this!

Tsunami detection is tricky, you best way is to be on the seabed then look for very small changes in pressure. There are already quite a few solution out there and I don’t think there is enough to gain to warrent further investigation.

Temperature and salinity would be easy enough to integrate, pH sensors are expensive.

You could use this with a set of temperature sensors for soliton detection which would be intersting.

No Pi has been to space officially, which requires reaching an altitude of at least 100 km/62.5 statute miles above sea level, the same distance needed to be reached in order to be recognized as an astronaut pilot, mission specialist, or, next year allegedly, tourist. The Pii in the Sky so far have made it almost a third of the way there, though.

I’ve just finished Mike Mullane’s “Riding Rockets” and a common theme is that you get your gold astronaut wings at 50 miles up (Mullane says that you should actually get them the moment the hold-down bolts blow, and after reading the book I tend to agree :))

So unless the US have recently gone all Euro-groovy and metric and FAI then I’m sticking with the country who has propelled more people further away from earth than anyone else ;)

I’m a Navy guy from the service that has produced more astronaut pilots than any other, as there’s just something about folks who can launch and recover from a runway/spot on a rolling, pitching deck welded to a hull … in the worst weather … at night … That includes the Marines, since they wear Navy wings, not Marine-specific wings since the Marine Corps is actually part of the Department of the Navy (their common leader is the civilian Secretary of the Navy).

We are particularly proud to have supplied the first American in space – not the much more famous Marine Lieutenant Colonel John Glenn, but Navy Commander Alan Shepard. Upon being asked by a reporter just before his suborbital Mercury-Redstone launch how it felt about to be the first American in space, Shepard replied with typical Navy carrier pilot humor, “How would you feel about to be strapped on top of a bomb built by the lowest bidder on a government contract?” This was after a series of well-publicized spectacular explosions during, or soon after, liftoff of about eight unmanned booster launches, most of them ironically using the Navy’s Vanguard design.

The shift to Redstone was within months before Shepard’s flight and it didn’t have a perfect record either, but it was better than Vanguard’s. It’s pretty obvious why John Glenn went into politics and was pretty successful at it, while Shepard could care less about the notoriety, bureaucracy, and phony-baloney back-slapping/stabbing associated with politics.

The Right Stuff is one of Eben’s favourite books. You know what a massive space geek he is; he was very, very pleased to see Al Shepard’s Corvette at Kennedy Space Center a few years ago (but the awe was overshadowed by the Saturn 5 in the same room…)

“So unless the US have recently gone all Euro-groovy and metric and FAI then I’m sticking with the country who has propelled more people further away from earth than anyone else”

Well the 100km figure (Karman Line) is based on various aerodynamic considerations apparently, and von Karman himself emigrated to the states, so counts as American. So I’m now even more confused which one is the real limit…

One word incredible. I have always imagined a ship like that. But just with a GPS and any long range connectivity setup (I don’t have any clue how to achieve this). Just to make it go around the pacific ocean and come back. Thanks for the blog.

The problems of waterproofing a Pi remind me of something I once read… The electronics package on the Lunar Rover was cast in wax. Apparently, it served as a heat sink without boiling away or damaging anything. I have to wonder if the nearly inevitable tiny leaks might not be thwarted by potting the Pi, etc., in wax… Obviously, connections would have to be taped or Plasti-dipped to keep the wax out…

Paraffin wax has at times been used in potting electronic assemblies directly. It is a good insulator, you don’t need to apply additional insulation. It has a tendency to crack, so you can’t really rely on it to make things completely waterproof.

There are many kinds of wax besides paraffin, and even various grades of paraffin. I was at a flight base of operations (FBO) doing the paperwork for a training flight. The fuel delivery guy came in and gave a bill to the desk clerk, saying, “Here’s the bill for your heating oil.” The clerk got a horrified look on their face and blurted out, “It was supposed to be Jet-A!” The delivery guy replied, “Oh, yeah, Jet-A, sorry. I did use the paraffin filter, so, don’t worry.” The main difference between heating oil and aviation kerosene is paraffin particulates that are suspended due to nearly identical density, but can be essentially all filtered out with a very fine metal mesh screen.

I’ve also heard of submerging marine electronics in mineral oil inside the enclosure. This keeps any salt water that may leak in, off the circuit, and it is not compressible so in some cases you don’t need your enclosure to be a pressure vessel.

That’s how sonar transducers and related components are kept out of trouble electrically as well free from corrosion, and it provides the necessary acoustic interface to carry the sound to/from transducers via the acoustically-transparent outer dome (on sophisticated systems).

“The electronics package on the Lunar Rover was cast in wax. Apparently, it served as a heat sink without boiling away or damaging anything.”
Yes, I think it was used for the batteries. The wax melted or at least softened, and the latent heat reduced the termperature rise. The phase change makes it more efficient than a normal heat sink. Lots of comments about this in the “apollo lunar surface journal” if you can read it all!

I think (might be wrong on this) the heat pipes used in fancy designer heatsinks works on a similar principle. (Might be liquid to gas though).

We don’t care whether it’s a “boy” or a “gull” :lol: If you want it pronounced “boy”, then spell it that way! The mess made of foreign place names relative to their native inhabitants’ actual pronunciation is proof enough that someone deserved to lose their place-name spelling license at the very minimum! ;) Don’t even get me started on materials names … aluminium??? I’m surprised but relieved that tin didn’t wind up as tinium, etc. :shock:

Having started out in ocean engineering, I can appreciate how difficult this is, although our stuff was going down upwards of 12,000 feet, the average depth of the oceans. Once you make it past the first 100 meters, or so though, and everything stays dry, it’s mostly a matter of packing more “monkey”, um, “stuff” around cables, etc., where they enter/exit the sealed unit. Openings are kept at/near the bottom of the pressure containment so that when, not if, even a small amount of corrosive/conductive seawater leakage occurs, it doesn’t dribble over/on anything on its inevitable meandering path to the bottom of the containment.

Sometimes that’s not practical, as when I served on a sub and seawater was discovered pretty much flowing in a sheet about an inch wide along the inside of the hull on its merry way to the bilge … right behind the sonar/comm electronics racks! This was on a Sturgeon “long hull” class of sub, which had an extra 10 feet of hull longitudinally amidships to allow additional electronics to be carried.

This coincidentally increased the living/eating/communal spaces and torpedo room on the lower two decks, making the nine subs so equipped marginally nicer to serve aboard. It also marginally increased the many ways to wind up dead on those subs, but boat crews are resigned to such a fate since they’re already entombed for months in their potential final resting place on the bottom of the ocean.

Those subs had a significantly higher incidence rate of leaks around the periscopes and radio masts – the one I was on had a periscope refitted three times over one Summer alone … Das Boot, indeed! :shock:

Hmm, my daughter may have a chance to attach a Pi to a sampling rosette in the Arctic this fall. That would allow for an extreme depth test. Which leads to two questions: 1) Pressure vessel construction? and 2) A task worthy of the effort?

I found this customized use for the Raspberry Pi very interesting. I was wondering if there are any details on the list of components used and the final “total” cost for one “marine conservation camera”?